Ideally, we would like to use $TRANSPARENT_FIGURES=1 in .latex2html-init and not set the page background to white. However, I have not been able to make this work. The failure is that I get various filled blotches in the figures. By setting both the figure and document backgrounds to white ($TRANSPARENT_FIGURES=0, $WHITE_BACKGROUND=1;, BGCOLOR="#FFFFFF"), this problem is made invisible. You may not have this problem. I think I have it because many of my PostScript figures use white-filled boxes to effectively ``erase'' lines (in the old NeXT Draw program); the transparent background conversion is supposed to be able to convert all occurrences of white to transparent, but I haven't been able to get this to work throughout my PostScript figures.
To try out transparent figure backgrounds, set $TRANSPARENT_FIGURES=1, and delete the string ``"BGCOLOR="#FFFFFF"'' in the $BODYTEXT variable. You may also need to set $WHITE_BACKGROUND=1;, I don't remember. Nothing works for me except white backgrounds for all.